The Cancer Epidemiology Program, historically one of the strongest programs in the USC/Norris Comprehensive CANCER Center (NCCC), includes 22 investigators who have successfully competed for peer reviewed support. In the past five years a total of 380 publications have resulted from the activities of Program members. Although the most widely recognized have been studies of the etiology of cancers of the breast, prostate and colon, publications have dealt with more than 30 different neoplasms, as well as a wide variety of different exposures, habits, genetic loci, resources, methodologies, and gene-environment interactions. Although investigators in the Program initially concentration largely upon the role of hormones in carcinogenesis, the Program is now broad-based with the emphasis gradually shifting to molecular epidemiology, especially in regards to interactions between heritable determinants and carcinogens to which persons are exposed by virtue of their personal of their collective environment.